Create procsysctl.c

added a new pkexec helper to modify values in /proc/sys, currently only can do writes to /proc/sys/kernel/split_lock_mitigate

util/procsysctl.c

@@ -0,0 +1,74 @@
+/*
+Copyright (c) 2017-2023, Feral Interactive
+All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+ * Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+ * Neither the name of Feral Interactive nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define _GNU_SOURCE
+#include <unistd.h>
+#include "common-logging.h"
+
+static bool write_value(char *key, char *value)
+{
+	FILE *f = fopen(key, "w");
+
+	if (!f) {
+		if (errno != ENOENT)
+			LOG_ERROR("Couldn't open file at %s (%s)\n", key, strerror(errno));
+
+		return false;
+	}
+
+	if (fputs(value, f) == EOF) {
+		LOG_ERROR("Couldn't write to file at %s (%s)\n", key, strerror(errno));
+		fclose(f);
+		return false;
+	}
+
+	fclose(f);
+	return true;
+}
+
+int main(int argc, char *argv[])
+{
+	if (geteuid() != 0) {
+		LOG_ERROR("This program must be run as root\n");
+		return EXIT_FAILURE;
+	}
+
+	if (argc == 3) {
+		if (strcmp(argv[1], "split_lock_mitigate") == 0) {
+			if (!write_value("/proc/sys/kernel/split_lock_mitigate", argv[2]))
+				return EXIT_FAILURE;
+
+			return EXIT_SUCCESS;
+		} else {
+			fprintf(stderr, "unsupported key: '%s'\n", argv[1]);
+			return EXIT_FAILURE;
+		}
+	}
+
+	fprintf(stderr, "usage: procsysctl KEY VALUE\n");
+	fprintf (stderr, "where KEY can by any of 'split_lock_mitigate'\n");
+	return EXIT_FAILURE;
+}